Biomedical electrodes are typically used in monitoring electrical impulses from the heart or brain. Conventional biomedical electrodes are generally disposable and comprise a pad member with an electrode projection on its top surface which is in electrical communication with a central portion of the bottom surface for making an electrical contact with a patient's skin. Typically, an adhesive material on the bottom surface surrounds the central portion and attaches the electrode in place. Biomedical electrodes are also typically used in providing electrical impulses for nerve or neuromuscular stimulation. Biomedical electrodes may also be used to deliver current, e.g., a defibrillation pad, in the event that the heart goes into fibrillation or to act as a ground during electrosurgery, e.g., a dispersive pad. Examples of such prior art biomedical electrodes are disclosed in U.S. Pat. Nos. 4,674,512 to Rolf; 4,834,103 to Heath; and 5,330,527 to Montecalvo et al.
Examples of biomedical electrodes which are configured to more securely attach an electrical lead wire to the electrode include, U.S. Pat. Nos. 4,331,153 and 4,757,817, both to Healy. In particular, the patents to Healy disclose an EKG electrode pad having a cut which allows an auxiliary portion of the pad to be lifted up and placed over the electrical lead wire which attaches to an electrode projection of the electrode.
U.S. Pat. No. 5,348,007 to Hitti discloses a biomedical electrode that will not easily be pulled from the skin of a patient when a force is exerted between the electrical lead wire and the patient. In particular, the biomedical electrode disclosed in Hitti includes a contact portion connected to a conductive bridge portion. The bridge portion is provided with a series of perforations or slits separated by small connections. The perforations form a break away means for the bridge portion which is used to pull the bridge portion apart, allowing it to expand, either immediately before or after the contact portion is applied to the patient's skin.
A drawback with the above-noted biomedical electrodes is that they are configured with a single or fixed surface area for contacting to a patient's skin. For example, when used in monitoring electrical impulses from a patient's heart or brain, a large number of electrodes are required to be attached to the patient's skin. Biomedical electrodes which have a fixed surface area for contacting to a patient's skin limit how close the biomedical electrodes can be spaced from each other. Such biomedical electrodes are also configured having a single or fixed surface area for establishing an electrical contact or ground with the patient's skin.
In addition, biomedical electrodes having the same contact size are typically packaged and sold in large volumes, e.g., to hospitals or government agencies. This limits purchases of biomedical electrodes having different contact sizes, and particularly, to less frequently used biomedical electrode sizes.
Therefore, there is a need for perforated biomedical electrodes having a surface area for contacting to a patient's skin which can be readily reduced in size allowing the electrode to be better suited for a particular application, e.g., initially being sized for use on an adult patient while having a readily removable portion that can be detached so that the biomedical electrode can be reduced in size for use on a child or small adult.